TKA Sagittal Plane (gap) Balancing

Question 1

What affect does upsizing the femoral component in TKA have on gaps?

Answer 1

Increases AP diameter and medial to lateral diameter.
Affects flexion if anterior referencing, PF if posterior referencing.
Does not affect extension gap

Question 2

Increasing poly size affects what gap(s)?

Answer 2

Both flexion and extension.

Question 3

Increasing tibia cut affects what gap(s)?

Answer 3

Both flexion and extension.

Question 4

TKA tight in flexion and extension?

Answer 4

Cut more proximal tibia.

Question 5

TKA tight in extension, balanced in flexion?

Answer 5

Release posterior capsule, resect more distal femur.

Question 6

TKA loose in flexion, tight in extension?

Answer 6

Resect more distal femur, shift femur posteriorly (if post. ref).
Resect more distal femur, upsize poly.

Question 7

TKA balanced in extension, tight in flexion?

Answer 7

Release PCL.

Downsize femur, shift anterior (if post. ref)

Question 8

TKA balanced in extension, loose in flexion?

Answer 8

Resect more distal femur, upsize poly.

Upsize femur and shift posteriorly (if post ref.)

Question 9

TKA loose in extension, tight in flexion?

Answer 9

Release PCL, upsize poly.

Question 10

TKA balanced in flexion, loose in extension?

Answer 10

Augment distal femur.

Question 11

TKA loose in extension, loose in flexion?

Answer 11

Increase poly size.

Question 12

Leaving a PCL substituting too loose in flexion and lead to what complication?

Answer 12

Cam-jump, or posterior knee dislocation.